Recently, a light-emitting element having a wide luminescence wavelength band is needed for optical sensing such as OCT (Optical Coherence Tomography). For example, a semiconductor light-emitting element having a hybrid structure of a quantum well and a quantum dot is supposed (for example, see Non-Patent Document 1). The semiconductor light-emitting element having the hybrid structure achieves a wide luminescence wavelength band by luminescence in which wavelengths from the quantum well and the quantum dot are different from each other. A strain field is formed around a self-formed quantum dot. It is known that when the strain field has influence on the quantum well layer, band gap energy of the quantum well layer changes (For example, see Non-Patent Documents 2 to 4).